Thermal tissue treatments are employed for a variety of different medical conditions. For example, radiofrequency (RF) and cryogenic ablation procedures are well recognized treatments for vascular and cardiac diseases such as atrial fibrillation, as well as for ablative treatment of cancerous tissue and other physiological conditions. The application of either RF or cryogenic treatment is usually based on the preference of the surgeon or the specific tissue to be treated. In either RF or cryogenic ablation, however, the location and quality of the lesion produced is a primary concern. The clinical success of a particular tissue ablation procedure depends on efficacy and safety of the application of the selected energy. Many factors influence lesion size such as tissue-electrode contact force, ablation energy level, and cooling factors, that is, blood flow rate, tissue perfusion, and the duration of energy delivery. Fast and accurate temperature acquisition can provide an important metric in delivering the proper amount of diagnostic and/or treatment energy to a tissue site. For example, the delivery of excessive energy in cardiac procedures can cause coagulum and/or damage adjacent tissues and structures such as the phrenic nerve or the esophagus of the patient. Insufficient energy delivery can result in poor lesion creation and low therapeutic success rates. Accordingly, thermocouples are often employed in proximity to a treatment region to provide the desired feedback to regulate power delivery.
However, during operation, thermocouples within a medical device may short-circuit. Shorts can be caused by a breakdown in the insulative barrier between individual conductors intended to be isolated. In addition, shorts can occur not only between multiple thermocouples, but also within a thermocouple consisting of a pair of wires. A thermocouple short circuit may be indicated by temperature variations between one or more thermocouples, but such temperature variations could also result from a change in blood flow or tissue contact with the medical device where the thermocouples are mounted. Accordingly, it may be difficult to distinguish between an actual short-circuit or channel fault of a particular thermocouple and a change in the physiological condition or environment of the medical device.